Belt Scrapers are used in bulk material handling belt conveyors to avoid material carry back, reduce spillage and keep belt clean. Clean belts help prevent material build up on snub pulley and return rollers and increase its life, thereby reducing cleaning cost, downtime cost and mis-tracking of the belt.
In first generation Counter weight belt scraper, single blade design is made from thick, rubber strip (wider than belt width) under the return belt and the counter weight provided at the side of the belt scraper with a pivot point to provide contact with the belt. The initial load exerted to the belt is approximately 80-90 Kgs. With time when the cleaning effectiveness reduces, the weight is increased and it can go up to 150 Kgs.
Cleaning efficiency is approx 60-68% and always, it is needed to increase counter weight load on a regular basis against blade wear. It is very less effective and high maintenance is involved.
Second generation fixed mount belt scraper's segmented blades module are made of hard alloy steel with rubber cushion at the bottom of blade mounted on a steel tube with both end fixed mount. It does not have automatic adjustments against blade wear. It provides inconsistent contact pressure to the belt which is approximately 100-125 Kgs.
Cleaning efficiency is approx 70-85% and always, there is need to lift-up of the fixed mount on a regular basis against blade wear. It is less effective and high maintenance involved.
Pneumatically operated third generation belt scraper having segmented blades module are made of hard alloy steel with or without polymer cushion at the bottom mounted of blade on a steel tube with ratchet and pinion mount and adjustment done through compressed air at 7-10 bars pneumatically. They provide inconsistent load to the belt of approximately 90-110 Kgs.
Cleaning efficiency is approx 75-85%. There is a need to pump air periodically to maintain the blade to belt contact due to drop in air pressure/leakage/chocking of air. Maintenance requirement is high.
In fourth generation belt scrapers with shock absorber which acts as semi automatic adjustments to some extent but, there is a need for periodic manual adjustments against blade wear in every 3-4 weeks interval. This type of belt scrapers have segmented type metallic blades module with pivot point below the scraping edge mounted on a steel tube with both ends rubber shock absorber. It provides comparatively less load to the belt, which is approximately 24-80 Kgs.
Cleaning efficiency is approx 92-95%. It provides less consistency against heavy duty, high speed, vibration and bi-directional belt operation.
Accordingly there was a long felt need to design belt scraper mountings which are maintenance free and long lasting and facilitates automatic adjustment in the field of bulk material handling conveyor systems to meet the increasing belt capacity (tonnages), higher belt speed and heavy duty of belt with wider belt conveying system.
The present invention meets the aforesaid long felt need.
All through out the specification including the claims, the words “conveyor belt”, “scraper blade” “scraper holding arm”, “spring”, “washer”, “stud”, and “nut” are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/Limitation if any, referred to the specification, is solely by way of example and understanding the present invention.